-
Notifications
You must be signed in to change notification settings - Fork 0
/
ParticleSystem.c
executable file
·313 lines (249 loc) · 10.6 KB
/
ParticleSystem.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
// The MIT License (MIT)
//
// Copyright (c) 2013 Dan Ginsburg, Budirijanto Purnomo
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
// Book: OpenGL(R) ES 3.0 Programming Guide, 2nd Edition
// Authors: Dan Ginsburg, Budirijanto Purnomo, Dave Shreiner, Aaftab Munshi
// ISBN-10: 0-321-93388-5
// ISBN-13: 978-0-321-93388-1
// Publisher: Addison-Wesley Professional
// URLs: http://www.opengles-book.com
// http://my.safaribooksonline.com/book/animation-and-3d/9780133440133
//
// ParticleSystem.c
//
// This is an example that demonstrates rendering a particle system
// using a vertex shader and point sprites.
//
#include <stdlib.h>
#include <math.h>
#include "esUtil.h"
#define NUM_PARTICLES 1000
#define PARTICLE_SIZE 7
#define ATTRIBUTE_LIFETIME_LOCATION 0
#define ATTRIBUTE_STARTPOSITION_LOCATION 1
#define ATTRIBUTE_ENDPOSITION_LOCATION 2
typedef struct
{
// Handle to a program object
GLuint programObject;
// Uniform location
GLint timeLoc;
GLint colorLoc;
GLint centerPositionLoc;
GLint samplerLoc;
// Texture handle
GLuint textureId;
// Particle vertex data
float particleData[ NUM_PARTICLES * PARTICLE_SIZE ];
// Current time
float time;
} UserData;
///
// Load texture from disk
//
GLuint LoadTexture ( void *ioContext, char *fileName )
{
int width,
height;
char *buffer = esLoadTGA ( ioContext, fileName, &width, &height );
GLuint texId;
if ( buffer == NULL )
{
esLogMessage ( "Error loading (%s) image.\n", fileName );
return 0;
}
glGenTextures ( 1, &texId );
glBindTexture ( GL_TEXTURE_2D, texId );
glTexImage2D ( GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, buffer );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE );
free ( buffer );
return texId;
}
///
// Initialize the shader and program object
//
int Init ( ESContext *esContext )
{
UserData *userData = esContext->userData;
int i;
char vShaderStr[] =
"#version 300 es \n"
"uniform float u_time; \n"
"uniform vec3 u_centerPosition; \n"
"layout(location = 0) in float a_lifetime; \n"
"layout(location = 1) in vec3 a_startPosition; \n"
"layout(location = 2) in vec3 a_endPosition; \n"
"out float v_lifetime; \n"
"void main() \n"
"{ \n"
" if ( u_time <= a_lifetime ) \n"
" { \n"
" gl_Position.xyz = a_startPosition + \n"
" (u_time * a_endPosition); \n"
" gl_Position.xyz += u_centerPosition; \n"
" gl_Position.w = 1.0; \n"
" } \n"
" else \n"
" { \n"
" gl_Position = vec4( -1000, -1000, 0, 0 ); \n"
" } \n"
" v_lifetime = 1.0 - ( u_time / a_lifetime ); \n"
" v_lifetime = clamp ( v_lifetime, 0.0, 1.0 ); \n"
" gl_PointSize = ( v_lifetime * v_lifetime ) * 40.0; \n"
"}";
char fShaderStr[] =
"#version 300 es \n"
"precision mediump float; \n"
"uniform vec4 u_color; \n"
"in float v_lifetime; \n"
"layout(location = 0) out vec4 fragColor; \n"
"uniform sampler2D s_texture; \n"
"void main() \n"
"{ \n"
" vec4 texColor; \n"
" texColor = texture( s_texture, gl_PointCoord ); \n"
" fragColor = vec4( u_color ) * texColor; \n"
" fragColor.a *= v_lifetime; \n"
"} \n";
// Load the shaders and get a linked program object
userData->programObject = esLoadProgram ( vShaderStr, fShaderStr );
// Get the uniform locations
userData->timeLoc = glGetUniformLocation ( userData->programObject, "u_time" );
userData->centerPositionLoc = glGetUniformLocation ( userData->programObject, "u_centerPosition" );
userData->colorLoc = glGetUniformLocation ( userData->programObject, "u_color" );
userData->samplerLoc = glGetUniformLocation ( userData->programObject, "s_texture" );
glClearColor ( 0.0f, 0.0f, 0.0f, 0.0f );
// Fill in particle data array
srand ( 0 );
for ( i = 0; i < NUM_PARTICLES; i++ )
{
float *particleData = &userData->particleData[i * PARTICLE_SIZE];
// Lifetime of particle
( *particleData++ ) = ( ( float ) ( rand() % 10000 ) / 10000.0f );
// End position of particle
( *particleData++ ) = ( ( float ) ( rand() % 10000 ) / 5000.0f ) - 1.0f;
( *particleData++ ) = ( ( float ) ( rand() % 10000 ) / 5000.0f ) - 1.0f;
( *particleData++ ) = ( ( float ) ( rand() % 10000 ) / 5000.0f ) - 1.0f;
// Start position of particle
( *particleData++ ) = ( ( float ) ( rand() % 10000 ) / 40000.0f ) - 0.125f;
( *particleData++ ) = ( ( float ) ( rand() % 10000 ) / 40000.0f ) - 0.125f;
( *particleData++ ) = ( ( float ) ( rand() % 10000 ) / 40000.0f ) - 0.125f;
}
// Initialize time to cause reset on first update
userData->time = 1.0f;
userData->textureId = LoadTexture ( esContext->platformData, "smoke.tga" );
if ( userData->textureId <= 0 )
{
return FALSE;
}
return TRUE;
}
///
// Update time-based variables
//
void Update ( ESContext *esContext, float deltaTime )
{
UserData *userData = esContext->userData;
userData->time += deltaTime;
glUseProgram ( userData->programObject );
if ( userData->time >= 1.0f )
{
float centerPos[3];
float color[4];
userData->time = 0.0f;
// Pick a new start location and color
centerPos[0] = ( ( float ) ( rand() % 10000 ) / 10000.0f ) - 0.5f;
centerPos[1] = ( ( float ) ( rand() % 10000 ) / 10000.0f ) - 0.5f;
centerPos[2] = ( ( float ) ( rand() % 10000 ) / 10000.0f ) - 0.5f;
glUniform3fv ( userData->centerPositionLoc, 1, ¢erPos[0] );
// Random color
color[0] = ( ( float ) ( rand() % 10000 ) / 20000.0f ) + 0.5f;
color[1] = ( ( float ) ( rand() % 10000 ) / 20000.0f ) + 0.5f;
color[2] = ( ( float ) ( rand() % 10000 ) / 20000.0f ) + 0.5f;
color[3] = 0.5;
glUniform4fv ( userData->colorLoc, 1, &color[0] );
}
// Load uniform time variable
glUniform1f ( userData->timeLoc, userData->time );
}
///
// Draw a triangle using the shader pair created in Init()
//
void Draw ( ESContext *esContext )
{
UserData *userData = esContext->userData;
// Set the viewport
glViewport ( 0, 0, esContext->width, esContext->height );
// Clear the color buffer
glClear ( GL_COLOR_BUFFER_BIT );
// Use the program object
glUseProgram ( userData->programObject );
// Load the vertex attributes
glVertexAttribPointer ( ATTRIBUTE_LIFETIME_LOCATION, 1, GL_FLOAT,
GL_FALSE, PARTICLE_SIZE * sizeof ( GLfloat ),
userData->particleData );
glVertexAttribPointer ( ATTRIBUTE_ENDPOSITION_LOCATION, 3, GL_FLOAT,
GL_FALSE, PARTICLE_SIZE * sizeof ( GLfloat ),
&userData->particleData[1] );
glVertexAttribPointer ( ATTRIBUTE_STARTPOSITION_LOCATION, 3, GL_FLOAT,
GL_FALSE, PARTICLE_SIZE * sizeof ( GLfloat ),
&userData->particleData[4] );
glEnableVertexAttribArray ( ATTRIBUTE_LIFETIME_LOCATION );
glEnableVertexAttribArray ( ATTRIBUTE_ENDPOSITION_LOCATION );
glEnableVertexAttribArray ( ATTRIBUTE_STARTPOSITION_LOCATION );
// Blend particles
glEnable ( GL_BLEND );
glBlendFunc ( GL_SRC_ALPHA, GL_ONE );
// Bind the texture
glActiveTexture ( GL_TEXTURE0 );
glBindTexture ( GL_TEXTURE_2D, userData->textureId );
// Set the sampler texture unit to 0
glUniform1i ( userData->samplerLoc, 0 );
glDrawArrays ( GL_POINTS, 0, NUM_PARTICLES );
}
///
// Cleanup
//
void ShutDown ( ESContext *esContext )
{
UserData *userData = esContext->userData;
// Delete texture object
glDeleteTextures ( 1, &userData->textureId );
// Delete program object
glDeleteProgram ( userData->programObject );
}
int esMain ( ESContext *esContext )
{
esContext->userData = malloc ( sizeof ( UserData ) );
esCreateWindow ( esContext, "ParticleSystem", 640, 480, ES_WINDOW_RGB );
if ( !Init ( esContext ) )
{
return GL_FALSE;
}
esRegisterDrawFunc ( esContext, Draw );
esRegisterUpdateFunc ( esContext, Update );
esRegisterShutdownFunc ( esContext, ShutDown );
return GL_TRUE;
}